The man accused of murdering Milly Dowler disappeared on the day the schoolgirl vanished, the Old Bailey has been told.

Levi Bellfield's former partner Emma Mills said she had tried to get hold of the 43-year-old nightclub bouncer but could not get through to his mobile phone.

Mills, 33, said: "He disappeared. His mobile was off. I was trying to get in touch with him because I didn't have any money and I needed to get some bits from the shop. Normally he would ring me or I would ring him, on and off during the day, to see what I was doing. He didn't ring me at all until later on. I didn't see him past lunchtime."

She said it was unusual for her not to be in contact with Bellfield, who was not working during the day at the time. She had a 40-second conversation with him at 5.38pm and a longer call later that evening, she said.

"I don't remember the actual conversation but I know how it probably went with me asking where he was all that time and when he was coming back."

Milly disappeared after leaving Walton-on-Thames railway station in Surrey to walk home along Station Avenue. The prosecution claims Bellfield was living yards away and murdered the girl in his flat before dumping the body. Six months later, her remains were found in woods 25 miles away.

Bellfield, who also worked as a wheel clamper, was convicted in 2008 of murdering Marsha McDonnell, 19, and Amelie Delagrange, 22, and attempting to murder Kate Sheedy, 18.

Mills said she met Bellfield at a club in Surrey when she was 18 and he was working on the door. She had moved into a flat in Collingwood Place in Walton-on-Thames with their two small children in 2001 and Bellfield had moved in by Christmas.

The week Milly vanished, the family were house-sitting for a friend in west London.

Mills gave evidence from behind a curtain shielding her from the defendant in the dock. The court was adjourned briefly when she began crying after hearing Bellfield clear his throat twice.

She told the court he returned to the friend's house between 10 or 11 that night, adding that he was wearing different clothes from those he had on in the morning.

"I think he got a takeaway and some lagers. He had had a drink but he was not drunk," she said.

Asked if she had questioned him, Mills answered: "I did but I would never get a straight answer – and even if he did tell me something, I would never know if it was the truth."

When the pair returned to Collingwood Place the following day, Mills noticed something unusual in the bedroom: "There were no sheets or pillow cases on the bed. No duvet cover. I rang him. He said the dog had had an accident on the bed. I didn't believe him for a second. I said, 'Why would she do that, when did it happen?'

"He said he put the sheets in the rubbish because they could not be washed."

Mills said Bellfield's Staffordshire bull terrier, Shy, would never have soiled the bed. When she looked in the bins outside the flat, she could see nothing, she said. The case continues.